functioning arduino software

for now, can enter:
[1 -1.5 ]*  moves axis 1 to -1.5 and checks has got there within a tol
[2 -1.3 ][1 1.5 ]* as above for both axes
[3]* gets the position of both axes
[4]* clears all commands

* is the 'execute' character
note that spaces are required to parse the double values correctly, not
sure why it can't detect a ] character as a termination character...